DESCRIPTION (Applicant's Description): The developing mammalian brain contains multipotential "stem" cells that differentiate into neurons and macroglial cells in response to soluble growth factors. In the past few years, several groups have identified functionally equivalent stem cells in the adult brain as well. An implication of these recent findings is an alternative hypothesis for the etiology of malignant astrocytomas, the most common primary brain tumors of adulthood. Traditionally thought to arise from the mutation and "de-differentiation" of mature astrocytes, they may instead arise from the disrupted differentiation and proliferation of residual stem cells. As a prelude to testing this hypothesis, the scientific goal of the current proposal is to better understand the genetic mechanisms regulating normal astrocyte development. Previously reported studies by others demonstrate that ciliary neurotrophic factor (CNTF) induces the differentiation of stem cells into astrocytes. The preliminary studies of the applicants indicate that the synthesis of immediate early genes is necessary for this process to occur. Some of these genes are likely to be transcribed in all growth factor-stimulated cells, but others only in cells undergoing differentiation into astrocytes. The specific aims of the project are to isolate and characterize astrocyte-unique immediate early genes. To do this the applicant will: 1) construct lambda cDNA libraries from naive and CNTF-stimulated CNS stem cells, 2) use plaque hybridization to identify CNTF-inducible immediate early genes, 3) classify the induced genes, 4) analyze their developmental expression, and 5) test their functions in vitro and in vivo. The long term goal of the project is to affect the differentiation and growth arrest of malignant astrocytomas by restoring the functions of lost or aberrent developmental genes. The training goals of this proposal are to learn how to isolate and characterize mammalian genes and to identify specific developmental and brain tumor-related genes for future study as an independent scientist. The laboratory the applicant has chosen will provide the ideal environment for this as it has an extensive experience in the study of immediate early genes and a strong commitment to neuro-oncology. The candidate's long term career plan is to investigate the molecular basis of brain tumor pathogenesis and contribute to the development of more effective therapeutic strategies.